This invention relates to a headphone of circumaural design in which, in use, the rim of a cup-shaped case, forming the coupling space, is engaged with the user's head and encloses the user's ear and, more particularly, to an improved headphone of circumaural design in which there are no reflecting surfaces.
At the present time, such circumaural headphones are in wide use since they provide physical comfort even for long periods of time and give the designer enough space for accommodating acoustic and/or electrical systems intended for improving the reproduction properties of the headphone.
Headphones of the prior art, however, have the disadvantage that up to date, they were unable to solve the problem of the "in-the-head-localization" of the acoustic event.
The present invention is directed to an improvement of both the directional and the distance hearing and, in addition, to the elimination of the disturbing phenomenon of the "in-the-head-localization." The inventive headphone is also suitable for audiometric purposes.
Known headphone constructions having the same objective, such as the designs of German Offenlegungsschrift Nos. 2,540,680 and 2,343,818, do improve the spatial hearing to some extent. However, they fail in reproducing the acoustic event sufficiently far to the outside or ahead in accordance with the real event so that, in general, and as before, the impression is produced, for example, during the reproduction of a piece of music, that the listener would be seated in the midst of the orchestra.
Close examinations and measurements at the auricle have shown that the external ear has the greatest bearing on the directional and distance perception. It has been further found that a sound reflecting surface, even of a very small area, for example, of 2 cm.sup.2 immediately adjacent the external ear, or of 1 cm.sup.2 close to the auditory canal, already causes linear distortions of the audio signals which unfavorably affect the directional and distance hearing.
Even if, in general, sound reflections can rightly be compared to optical reflections, it is important to be aware of the fact that, with sound reflections, the reflecting surface is perceived as the location where the sound wave is produced.